In examining the findings of "Pygmalion in the Classroom," an experimental study of the positive effects of favorable teacher expectations on the intellectual development of disadvantaged elementary school students, this review speculates about why the experimental students, whom the teachers expected to improve, and the control students, who were not designated as "spurters", both were able to make gains in their scores on an intelligence test. It is felt that this finding can be attributed to the impact and influence of the experimental students on the controls in the heterogeneously grouped classrooms and to the determination of individual experimental and control students, regardless of the expectations of their teachers. Evidence for this second speculation is based on the finding that not all the experimentals showed IQ gains, some even decreased, and that some control students matched the top IQ scores of the experimentals. (EF)